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<h2 id="CeWolfchartsusingVelocitytemplates-SetupCeWolf">Setup CeWolf</h2>
<p><strong>This currently only works with the most recent CVS version of WebWork but should be available in the upcoming 2.0 beta2</strong></p>
<ol><li>Go to <a shape="rect" class="external-link" href="http://cewolf.sourceforge.net" rel="nofollow">http://cewolf.sourceforge.net</a> and grab a stable release of CeWolf (at the time of writing, the unstable builds do not work with WebWork).</li><li>Edit your webwork.properties file and add "de.laures.cewolf.taglib.tags" to the  property "webwork.velocity.tag.path"</li></ol>


<p>Lastly add the CeWolf servlet to web.xml:</p>

<div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
<pre class="brush: java; gutter: false; theme: Default" style="font-size:12px;">
&lt;servlet&gt;
    &lt;servlet-name&gt;CewolfServlet&lt;/servlet-name&gt;
    &lt;servlet-class&gt;de.laures.cewolf.CewolfRenderer&lt;/servlet-class&gt;
&lt;/servlet&gt;

&lt;servlet-mapping&gt;
    &lt;servlet-name&gt;CewolfServlet&lt;/servlet-name&gt;
    &lt;url-pattern&gt;/cewolf/*&lt;/url-pattern&gt;
&lt;/servlet-mapping&gt;
</pre>
</div></div>
<h2 id="CeWolfchartsusingVelocitytemplates-CreateaDatasetProducer">Create a DatasetProducer</h2>
<p>This is the default DatasetProducer from the CeWolf tutorial.</p>

<div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
<pre class="brush: java; gutter: false; theme: Default" style="font-size:12px;">
import java.io.Serializable;
import java.util.Date;
import java.util.Map;

import org.jfree.data.DefaultCategoryDataset;

import de.laures.cewolf.DatasetProduceException;
import de.laures.cewolf.DatasetProducer;

public class PageViewCountData implements DatasetProducer, Serializable {

	// These values would normally not be hard coded but produced by
	// some kind of data source like a database or a file
	private final String[] categories =    {"mon", "tue", "wen", "thu", "fri", "sat", "sun"};
	private final String[] seriesNames =    {"cewolfset.jsp", "tutorial.jsp", "testpage.jsp", "performancetest.jsp"};
	private final Integer[] [] values = new Integer[OS:seriesNames.length] [OS:categories.length];

	public Object produceDataset(Map params) throws DatasetProduceException {
		DefaultCategoryDataset dataset = new DefaultCategoryDataset();
		for (int series = 0; series &lt; seriesNames.length; series ++) {
			int lastY = (int)(Math.random() * 1000 + 1000);
			for (int i = 0; i &lt; categories.length; i++) {
				final int y = lastY + (int)(Math.random() * 200 - 100);
				lastY = y;
				dataset.addValue((double)y, seriesNames[OS:series], categories[i]);
			}
		}
		return dataset;
	}

	public boolean hasExpired(Map params, Date since) {		
		return (System.currentTimeMillis() - since.getTime())  &gt; 5000;
	}

	public String getProducerId() {
		return "PageViewCountData DatasetProducer";
	}
}
</pre>
</div></div>
<h2 id="CeWolfchartsusingVelocitytemplates-CreatetheVelocitytemplate">Create the Velocity template</h2>
<p>With the new WebWork refactorings, nested JSP tags with arbitrary parameters can be used, so we convert the CeWolf tutorial JSP script to Velocity.</p>

<div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
<pre class="brush: java; gutter: false; theme: Default" style="font-size:12px;">
&lt;jsp:useBean id="pageViews" class="de.laures.cewolf.example.PageViewCountData"/&gt;
&lt;cewolf:chart 
    id="line" 
    title="Page View Statistics" 
    type="line" 
    xaxislabel="Page" 
    yaxislabel="Views"&gt;
    &lt;cewolf:data&gt;
        &lt;cewolf:producer id="pageViews"/&gt;
    &lt;/cewolf:data&gt;
&lt;/cewolf:chart&gt;

&lt;cewolf:img chartid="line" renderer="cewolf" width="400" height="300"/&gt;
</pre>
</div></div>

<p>In Velocity it looks like this:</p>
<div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
<pre class="brush: java; gutter: false; theme: Default" style="font-size:12px;">
#set( $pageViews = $stack.findValue("new com.PageViewCountData()") )
$req.session.setAttribute("pageViews", $pageViews ) 

#bodytag( SimpleChart "id=line" "title=Page View Statistics" "type=line" "xaxislabel=Page" "yaxslabel=Views" )
  #bodytag( Data )
    #tag( Producer "id=pageViews" )
  #end
#end

#tag( ChartImg "chartid=line" "renderer=cewolf" "width=400" "height=300" ) 
</pre>
</div></div>

<p>As you may notice, CeWolf looks up it's DatasetProducer in the request attributes - it has no knowledge of the Velocity context. That's why we call $req.session.setAttribute(). The other attributes (such as the chartid) will be set by CeWolf, so we don't need to care about them.</p>
<h2 id="CeWolfchartsusingVelocitytemplates-Setupanactiontodisplythetemplate">Setup an action to disply the template</h2>
<p>Now you should be able to fire up an action in the usual way with this template as the result and a nice chart should appear.</p></div>
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